Blood-brain barrier filter exchange imaging (BBB-FEXI) detects altered water exchange rates in cerebral small vessel disease

Motivation: Cerebral small vessel disease (cSVD) is a chronic condition affecting the brain microvasculature; subtle blood-brain barrier (BBB) damage is increasingly recognised as a key mechanism in its pathogenesis. Water exchange (WEX) rate measurement techniques are emerging as potential alternatives to conventional gadolinium contrast-enhanced approaches, and may provide a more sensitive assessment of subtle BBB dysfunction. Goal(s): To assess BBB WEX rates in cSVD. Approach: We use the BBB filter exchange imaging (BBB-FEXI) technique to measure WEX rates in ten cSVD and ten healthy controls. Results: Higher WEX was observed in cSVD subjects than in healthy controls. Impact: BBB-FEXI was sensitive to BBB water exchange and microstructural alterations in cSVD. This may provide insight into the diffuse and heterogeneous disease process of cSVD, where there is often minimal agreement between clinical and radiological findings, ultimately improving patient prognosis.